BLEND DOOR ACTUATOR MOTOR
The blend door actuator motor is located on rear of A/C evaporator housing. It controls A/C temperature blend door movement on command from the EATC module. Internally, an electronic circuit accepts commands from mode control buttons and positions A/C temperature blend door through an electric motor. An integral potentiometer feeds temperature blend door position information back to control panel.
EATC MODULE
The EATC module consists of a digital display, temperature and mode control buttons, and a blower speed control button. The temperature can be increased with up arrow button up to 85°F (29°C) or decreased with down arrow button down to 65°F (18°C). (Scheme 7) Trouble codes can be displayed by simultaneously pushing OFF and FLOOR button, then AUTOMATIC button within 2 seconds.
When AUTOMATIC setting is selected, AUTO and set temperature will be shown in the EATC display window. (Scheme 7) System maintains set temperature by controlling airflow direction, airflow quantity and discharge temperature required for comfort.
Mode buttons on lower edge of EATC module override automatic function. (Scheme 7) The override buttons affect operation as follows
MAX A/C
Pressing MAX A/C button will display MAX A/C and selected temperature in display window. Blower will run at high speed, and recirculation function will be activated. A/C clutch will operate if ambient temperature is approximately 50°F (10°C) or more.
Vent
Pressing vent button will display panel airflow image and will admit only outside air. No cooling is allowed, but air temperature can be heated and blower speed can be manually adjusted. Compressor will be off. Outside air is directed to panel vents.
Panel/Floor
Pressing panel/floor button will display panel and floor airflow image and will admit outside air. Floor/panel door will be in partial vacuum position, allowing air from floor outlet, center console and panel vents. No air bleed to defrost position will be allowed. Some airflow is directed to side window demister vents. Compressor and blower motor are running.
Floor
Pressing floor button will display floor image. Outlet air will enter and flow from floor vents at center console and heater outlet. Temperature of air can be heated, but not cooled. Compressor is off. Blower motor speed can be manually adjusted.
Floor/Defrost
Pressing floor/defrost button will display floor and defrost images. Outside air will be equally distributed to floor and defrost vents, with a small amount of air going to side window demisters. Compressor will operate if ambient temperature is approximately 50°F (10°C) or more. Blower motor speed can be manually adjusted.
FRONT Defrost
Pressing FRONT defrost button will display defrost indicator and displays selected temperature. Outside air will be directed to defrost vents, with a small amount going to floor ducts and side window demisters. The A/C compressor will operate if ambient temperature is approximately 50°F (10°C) or more. Blower motor speed can be manually adjusted.
Scheme 7
Scheme 8
Ambient Temperature Sensor
Sensor contains a thermistor (temperature sensitive resistor), which measures outside air temperature and inputs signal to EATC module. Ambient temperature sensor is located in front of condenser, on radiator support.
In-Car Temperature Sensor (Automatic Temperature Control Sensor)
Sensor contains a thermistor (temperature sensitive resistor), which measures temperature inside vehicle and inputs signal to EATC module. In-car temperature sensor is located behind instrument panel, left of radio.
Sunload Sensor
Sunload sensor contains a photovoltaic (sunlight sensitive) diode, which measures sunlight entering vehicle and inputs signal to EATC module. Sensor is located on upper right instrument panel, above glove box.
BLOWER MOTOR SPEED CONTROLLER
Blower motor speed controller is located under evaporator housing, left of blower motor. The controller converts low current signals from EATC module to a high current, variable ground feed to the blower motor. Blower motor speed is controlled by EATC module and blend door actuator position.
A delay function provides gradual increase or decrease in blower motor speeds. High-speed blower relay, integral with blower motor speed controller, gives maximum airflow in high blower position.
Note. DO NOT operate system with blower motor disconnected, or blower motor speed controller may be damaged.
ELECTRONIC BLEND DOOR ACTUATOR
Located on rear of evaporator housing, electronic blend door actuator is designed to move air temperature blend doors on command from EATC module. Electronic blend door actuator contains a reversible electric motor and potentiometer to move temperature blend door. A 5-volt signal is applied to ends of potentiometer, and a variable voltage at wiper arm indicates position of potentiometer, which ultimately drives actuator to proper position.
PRESSURE RELIEF VALVE
Pressure relief valve relieves high-side pressure build-up and prevents damage to A/C compressor and other system components. Pressure relief valve is located on manifold and tube assembly.
VACUUM ACTUATORS
Vacuum actuators control movement of air distribution doors. Two of the vacuum actuators are mounted on plenum. One vacuum actuator controls movement of the floor/panel door. A second vacuum actuator is used for panel/defrost door.
Another vacuum actuator, mounted on the fresh/recirculated air duct, controls movement of fresh/recirculated air door.
On 5-passenger models, an additional vacuum actuator is mounted on the heater plenum. This actuator controls airflow to rear seat register.
A/C CYCLING SWITCH
Mounted on Schrader valve on top of accumulator-drier so that suction pressure controls opening and closing cycle of switch. Switch controls evaporator core temperature to prevent evaporator icing. Switch opens when suction pressure is 22-28 psi (1.5-2.0 kg/cm 2 ).A/C cycling switch closes when suction pressure rises to about 40-47 psi (2.8-3.3 kg/cm 2 ).
Scheme 9
* PLEASE READ FIRST *
The EATC module self-test will detect problems in system control functions. It will display hard DTCs and intermittent DTCs during system operation.
If EATC module cannot be accessed by NGS tester, go to TEST A: NO COMMUNICATION WITH EATC MODULE . Or, if EATC module self-test will not detect concerns associated with DLC messages, an NGS tester will have to be used to retrieve these messages.
A/C SYSTEM PERFORMANCE
- Park vehicle out of direct sunlight. Connect manifold gauge set. Start and run engine at 1500 RPM. Set A/C controls to MAX A/C and maximum cold setting.
- Set blower/fan on high speed. Close doors and windows. Insert thermometer in center vent. Operate system for 10 minutes to allow system to stabilize. Measure center vent output temperature. See «A/C SYSTEM PERFORMANCE SPECIFICATIONS»(ref-40037-S40122008302001100500000) table.
- At about 68°F (20°C) ambient temperature, high side pressures should be approximately 100-200 psi (7.0-14.1 kg/cm 2 ). Low side pressures should be approximately 24-46 psi (1.7-3.2 kg/cm 2 ).
- As low side pressure decreases, high side pressure should increase. When A/C clutch disengages, low side pressure will increase and high side pressure should decrease. See «A/C SYSTEM HIGH SIDE PRESSURE SPECIFICATIONS»(ref-40037-S12826597992001100500000) table.
| Ambient Temperature °F (°C) | Outlet Air Temperature °F (°C) |
|---|---|
| 59 (15) | 34-46 (1-8) |
| 68 (20) | 34-46 (1-8) |
| 77 (25) | 34-46 (1-8) |
| 86 (30) | 34-46 (1-8) |
| 95 (35) | 36-48 (2-9) |
A/C SYSTEM PERFORMANCE SPECIFICATIONS
| Ambient Temp. °F (°C) | Psi (kg/cm2) |
|---|---|
| 60 (16) | 75-175 (5.3-12.3) |
| 70 (21) | 100-200 (7.0-14.1) |
| 80 (27) | 128-230 (8.9-16.1) |
| 90 (32) | 150-260 (10.5-18.3) |
A/C SYSTEM HIGH SIDE PRESSURE SPECIFICATIONS
HEATER CORE
- Check for proper coolant level. Start engine and turn heater ON. When engine reaches normal operating temperature, feel heater outlet hose. It should be hot. If not, heater core may have an air pocket, heater core may be plugged, or thermostat may not be working properly.
- Drain cooling system. Disconnect heater hoses from heater core. Install short piece of heater water hose, about 4 in. (101 mm) long on each heater core tube. (Scheme 10)
- Fill heater core and heater water hoses with water. Install Plug (BT-7422-B) on end of hose and Adapter (BT-7422-A) on other end. (Scheme 10) Secure hoses to core tubes, plug, and adapter with hose clamps.
- Attach pump and gauge assembly from a radiator/heater core pressure tester to adapter fitting on heater hose. Close tester bleed valve and apply 35 psi (2.46 kg/cm 2 ) air pressure to heater core. Watch gauge for 3 minutes.
- If pressure drops, check all hose clamp connections for proper fit; replace leaking hoses or clamps. If hoses do not leak, remove heater core from vehicle.
